Detection of designer steroid methylstenbolone in “nutritional supplement” using gas chromatography and tandem mass spectrometry: Elucidation of its urinary metabolites

► Detection of designer steroid methylstenbolone in “nutritional supplement”. ► Identification of two long-term 16-hydroxylated methylstenbolone metabolites. ► Good targets to monitor methylstenbolone misuse in doping control analysis. ► Elucidation of metabolites structures using gas chromatography and tandem mass spectrometry.